Peripheral endocannabinoid system activity in patients treated with sibutramine.

Objective: The endocannabinoid system (ECS) promotes weight gain and obesity-associated metabolic changes. Weight loss interventions may influence obesity-associated risk indirectly through modulation of the peripheral ECS. We investigated the effect of acute and chronic treatment with sibutramine on components of the peripheral ECS.

Methods And Procedures: Twenty obese otherwise healthy patients received randomized, double-blind, crossover treatment with placebo and 15 mg/day sibutramine for 5 days each, followed by 12 weeks open-label sibutramine treatment. We determined circulating anandamide and 2-arachidonoylglycerol and expression levels of endocannabinoid genes in subcutaneous abdominal adipose tissue biopsies.

Results: Body weight was stable during the acute treatment period and decreased by 6.0+/-0.8 kg in those patients completing 3 months of sibutramine treatment (P<0.05). Circulating endocannabinoids and the expression of ECS genes did not change with acute or chronic sibutramine treatment.

Discussion: The ECS is activated in obesity. We did not find any influence of 5% body weight loss induced by sibutramine on circulating levels of endocannabinoids and adipose-tissue expression of endocannabinoid genes in obese subjects. These data confirm our previous findings on dietary weight loss and suggest that the dysregulation of the ECS may be a cause rather than a consequence of obesity.